1. Field of the Invention
The present invention relates to a display screen switch which is operated above a display screen for displaying an image indicating switch information.
The present application is based on Japanese Patent Applications Nos. Hei. 10-371600 and 11-155381, the contents of which are incorporated herein by reference.
2. Description of the Related Art
FIG. 19 is a front view showing a related electric apparatus for a vehicle. Referring to FIG. 19, an operation panel 1 is secured to the front surface of a casing. A display unit 2 is disposed in the central portion of the operation panel 1. A variety of switches 3 are disposed around the display unit 2. The overall display screen of the display unit 2 serves as a display area 4. Various information are displayed on the display area 4 as an image. In accordance with, for example, displayed information, the switch 3 is operated.
In recent years an attempt has been made to realize a switch having a multiplicity of functions. Therefore, a display screen switch has been suggested which displays an image indicating switch information on the display screen of the display unit 2 and which is operated on the display screen. The display screen switch includes a touch-panel-type switch having a touch panel disposed on the display screen and arranged to be depressed and a contact-type switch including a transparent operation members provided for the display screen and arranged to be depressed to operate the switch. The touch panel switch has substantially no operation stroke when the depression is performed. Therefore, a satisfactory input feeling cannot be obtained. On the other hand, the switch incorporating the transparent operation members and the contact-type switches permits a sufficiently long operation stroke when the depression is performed. Therefore, the foregoing problem can be overcome.
The related display-screen switch incorporating the transparent operation members and the contact-type switch has a problem in that an image indicating switch information displayed on the display screen 2a cannot easily be viewed. That is, the distance L from the display screen 2a of the display unit 2 to the upper surface (key top) 5a of the transparent operation plate 5 is too long, as shown in FIG. 20. Therefore, when a surface on which usual characters have been printed serves as the upper surface (key top) 5a of the transparent operation plate, an image of switch information displayed on the display screen 2a is viewed far. Thus, this means only poor legibility.
In view of the foregoing, it is an object of the present invention to provide a display screen switch which is able to shorten the distance from the display screen to the key top and permits satisfactory legibility.
To achieve the above object, according to the first aspect of the present invention, there is provided a display screen switch disposed above a display device that includes a display screen and is capable of displaying on the display screen an image that indicates various information comprising switch information, the switch which includes a casing disposed above a display screen and having a circuit, the casing including a plate-like casing body disposed on the display screen and a transparent window portion formed to penetrate the casing body from a surface side to a reverse side thereof, a switch body disposed on the casing body, the switch body being connected to the circuit, and a transparent operation plate disposed above the surface side of the casing body, the transparent operation plate being depressed so as to operate the switch body, wherein an image of switch information displayed on the display screen is transmitted to the transparent operation plate through the transparent window portion of the casing. The foregoing display screen switch has the structure that the casing and the transparent operation plate, which are stacked, are disposed on the display screen of the display device. When the transparent operation plate is depressed, the switch body secured to the casing is operated. Therefore, the distance from the display screen to the transparent operation plate, which is the key top, can be shortened. As a result, a structure having a small thickness can be realized and an image of switch information displayed on the display screen can easily be viewed.
According to the second aspect of the present invention, it is preferable that the transparent operation plate includes a transparent display portion wherein the image of the switch information displayed on the display screen is transmitted through and also displayed on the transparent display portion, a secured portion disposed on one side of the transparent display portion and secured to the casing body, an elastic portion disposed between the secured portion and the transparent display portion, and a switch depression portion disposed on the other side of the transparent display portion and disposed above the switch body. In addition to the effect obtainable from the first aspect, the foregoing display screen switch has the structure that when the transparent display portion of the transparent operation plate is depressed, elastic deformation of the elastic portion causes the switch depression portion to press the switch body. After the pressure has been suspended, elastic restoring deformation of the elastic portion causes the switch body to be returned. Since the elastic portion serving as a restoring device is provided on either side of the transparent display portion, a necessity for interposing a restoring device between the transparent operation plate and the casing can be eliminated. Therefore, the transparent-operation plate can be disposed adjacent to the casing. Hence it follows that an image of switch information displayed on the display screen can furthermore easily be viewed.
According to the third aspect of the present invention, it is preferable that a plurality of the transparent window portions are provided in the casing body, a plurality of the transparent operation plates corresponding to the plural transparent window portions are integrally formed together, and a plurality of the switch bodies arranged to be operated by the plural transparent operation plates are provided. In addition to the effects obtainable from the first and second aspects, the display screen switch including the plural transparent operation plates and the corresponding switch bodies permits a plurality of inputs.
According to the fourth aspect of the present invention, it is preferable that the switch depression portion and the transparent display portion are substantially same in height from the casing body. In addition to the effects obtainable from the second aspect or the third aspect, the distance from the casing to the transparent display portion can be made to be substantially the same height as that of the switch body. As a result, a structure having a small thickness can be realized and an image of switch information displayed on the display screen can furthermore easily be viewed.
According to the fifth aspect of the present invention, it is preferable that the transparent operation plate includes a transparent display portion wherein the image of the switch information is transmitted through and displayed on the transparent display portion, a switch depression portion disposed on one side of the transparent display portion and disposed above the switch body, and a flange portion formed around the transparent display portion and the switch depression portion, and the switch further comprises a cover disposed above the casing wherein the transparent operation plate is disposed between the cover and the casing while the transparent display portion and the switch depression portion are projected through an opening for the operation plate of the cover, and an elastic member is interposed between the transparent operation plate and the casing around the transparent operation plate, wherein the elastic member is brought into hermetic contact with the transparent operation plate due to elastic reactive force of the elastic member. In addition to the effect obtainable from the first aspect, when the switch depression portion of the transparent operation plate is depressed, the elastic member is elastically deformed in the downward direction. Thus, the switch body is operated. When the depression of the switch depression portion is inhibited, the elastic restoring deformation of the elastic member causes the switch depression portion to be returned to the original position. The elastic member is disposed below the overall outer surface of the transparent operation plate, the elastic member is being brought into hermetic contact with the transparent operation plate owing to the elastic reactive force of the elastic member. Therefore, introduction of dust, water or the like introduced through the opening of the cover operation plate can be prevented.
Other objects, features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.